One of the most influential logicians of the day has assembled and in part rewritten a number of his essays on important questions of logical theory.1 The result is a most impressive book, at once powerful and graceful, and breathing a certain intellectual hauteurr which accords well with its conspicuous property of being intellectually first rate. These are not humble analytical gropings, undertaken by the dim light of an author’s sense of the sensible; but a series of campaigns in abstract metaphysics, directed from the firm ground of mastery of a rigorous and exacting technique. “Those of us who have a taste for desert landscapes” is a phrase of the author’s. With a Roman ruthlessness he makes a solitude in which he can quantify peacefully over lumps of rock.